Mosquitoes that have made their way to the Galapagos Islands via tourist planes and boats are threatening the rare native species endemic to the region, according to a study published in the journal Proceedings of the Royal Society B.

Culex quinquefasciatus, known as the southern house mosquito, can carry diseases dangerous to wildlife, such as avian pox and West Nile virus. Not only have the insects hopped a ride onto the islands, but they’ve also bred with native species once they reach the shore, the study found. That means they pose an ongoing threat to the Galapagos’ rare species and delicate ecosystem, which inspired Darwin’s theory of evolution after he observed the island’s unique array of wildlife. “You only need a single infectious mosquito to initiate a disease cycle,” [co-author Simon] Goodman…[T]he Galapagos “have globally important biodiversity — endemic species found nowhere else in the world,” said Goodman [Telegraph].

Tourism provides a significant amount of income for the Galapagos, and tourism is increasing by about 14 percent each year. But more non-native mosquitoes also up the risk of new diseases and the potential for environmental catastrophe. Such a disaster occurred in Hawaii during the late 1800s when the southern house mosquito came to the island via whaling ships, passing along diseases that wiped out bird species. After the dust settled, a mere 19 of the original 42 species of a bird known as the honeycreeper remain in Hawaii. The researchers fear everything is in place for a similar wipe-out in the Galapagos, given the rapid growth in transport links with the mainland…. “That we haven’t already seen serious disease impacts in Galapagos is probably just a matter of luck” [Reuters], Goodman said.

To determine whether the mosquitoes were coming onto the island–and staying there–researchers looked “for insects in aircraft holds and genetic analysis of the mosquito populations. The former allows [scientists] to quantify the arrival rates of mosquitoes on aeroplanes, and the latter allows [them] to estimate how many survive and spread around the islands once in Galápagos” [Guardian], co-author Arnaud Bataille said. The scientists emphasized the need for tighter government provisions to prevent new species from invading the islands; the mosquitoes are just one of many that have made their way to the Galapagos, along with rats, flies, and various plants.

The news comes just in time for World Mosquito Day, which was founded in an effort to boost awareness of the importance of keeping mosquito populations in check because of the diseases the insects can pass to humans and animals alike—the Galapagos being a sad and timely example thereof.